The chief executive of Johnston Press has warned that more titles will close and that further job losses – on top of last year's 15% reduction in the workforce – will be necessary in the next 12 months at the regional publishing group.

The publisher of the Scotsman and the Yorkshire Post said today it had suffered the "greatest fall in revenue in its history" in 2008 as income dropped 12.4% to £531.9m despite rampant cost cutting that saw staff numbers cut from 7,538 to 6,408 by December.

John Fry told MediaGuardian.co.uk the next 12 months would be a "very challenging year" and that he expected further job losses, although he would not specify a figure, and that a number of weekly newspapers were likely to close.

"I'm sure there will be closures in the next 12 months but we don't have plans for any large-scale closures," he said.

Fry said that despite a spate of recent heavy job losses and consolidation in the weekly newspaper business, he still thought it had a "very strong future".

Johnston Press is looking to ease its debt burden by selling a number of its Irish titles. Fry said the possible sale of the Irish papers, which include the Leinster Leader series, arose after the publisher was approached by a potential buyer. The company expects to receive offers of interest from all prospective buyers by 19 March, he added.

However, he dismissed speculation around the possible sale of leading titles the Yorkshire Post and the Scotsman, which Johnston Press bought for £160m in 2005.

He went on to advocate change to the competition law that limits regional publishers' interests in other local media businesses, saying current rules are "much too simplistic".

He said the Office of Fair Trading had in the past looked at newspaper groups in isolation from other advertising-driven businesses. But he dismissed the idea that changes to the current regulation might be necessary to help companies through the advertising downturn.

"I don't think that we need mergers to get through the economic downturn. But they do create business because companies can become even more cost efficient. I suppose that helps when there is pressure," he added.

Fry was confronted this morning in London by journalists from Johnston Press's Yorkshire Post – who are almost a fortnight into a strike action.

The protesters handed out leaflets to senior management detailing how Yorkshire Post Newspapers made a £25m profit last year but that staff had been frustrated since the takeover by Johnston Press and what they called "massive underinvestment in our papers".

"We believe Johnston Press must reverse its catastrophic policies by investing in journalism, selling and marketing our newspapers to untapped audiences and by making major improvements to our digital services," the leaflets said.

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